Log construction failures for user-defined parameters in operation handlers to improve error diagnosis.

[drganjoo]

An operation handler can accept user-defined data types as long as they implement FromParts. This trait has an associated type called Rejection, which is used to signal an error if the user-defined data type cannot be constructed from the request.

Similarly, FromRequest is used by the framework to construct input/output structures (and their members) from the request. If it fails to do so, it raises an error using its Rejection associated type.

For example, if FromRequest fails to construct a parameter because Extension<State> is expected by the user-defined operation handler, but Extension<Arc<State>> is actually added by the extension layer, the server does not currently log a message indicating this construction failure. Instead, it simply returns a 500 Internal Server Error.

To improve troubleshooting, the server should log an entry to help users identify when a parameter could not be constructed.

[drganjoo]

#3378